The utility of 5.56mm is hard to beat. If you want a .22 caliber round that reaches out further for target shooting or varmint hunting then 22 ARC is what you need. – Designed for the AR15 platform this 16.1 22 ARC barrel is ready for your next build. – Caliber .22 ARC – Barrel Length 16.1 – Barrel Twist 1:7 – Barrel Contour MT – Barrel Material 4140CM Nitride Finish – Barrel Twist 1:7 – Muzzle Thread 1/2 x 28 – Gas Port Location Rifle